A Study of JNJ-75276617 in Combination With Conventional Chemotherapy for Pediatric and Young Adult Participants With Relapsed/Refractory Acute Leukemias

Inclusion Criteria:

Acute leukemia harboring histone-lysine N-methyltransferase 2A (KMT2A) or nucleophosmin 1 gene (NPM1) or nucleoporin (NUP98 or NUP214) alterations
Performance status greater than or equal to (>=) 50 by lansky scale (for participants less than [<] 16 years of age) or >=50 percent (%) karnofsky scale (for participants >=16 years of age)
Estimated or measured glomerular filtration rate >= 60 milliliter per minute per 1.73 meter square (mL/min/1.73m^2) based on the bed side schwartz formula

Exclusion Criteria:

Received an allogeneic hematopoietic transplant within 60 days of screening
Active acute graft-versus-host disease of any grade or chronic graft-versus-host which is not well-controlled
Received immunosuppressive therapy post hematopoietic transplant within 30 days of enrollment
Diagnosis of Down syndrome associated leukemia, acute promyelocytic leukemia, juvenile myelomonocytic leukemia
Diagnosis of fanconi anemia, kostmann syndrome, shwachman diamond syndrome, or any other known bone marrow failure syndrome
Prior exposure to menin-KMT2A inhibitors
Prior cancer immunotherapy (ie [that is], Chimeric Antigen Receptor-T Cell Therapy [CAR-T], inotuzumab, gemtuzumab ozogamicin) within 4 weeks prior to enrollment or blinatumomab within 2 weeks prior to enrollment. Additional prior cancer therapies must not be given within 4 weeks prior to enrollment or 5 half-lives of the agent (whichever is shorter)